Air conditioner and driving method thereof

ABSTRACT

An air conditioner comprises: a first compression unit (C 1 ) and a second compression unit (C 2 ) for respectively compressing a refrigerant; an outdoor heat exchanger ( 200 ) provided at an outdoor unit and connected via the secondcontrol valve ( 400 ) to the first compression unit (C 1 ) and the second compression unit (C 2 ); and indoor heat exchanger ( 100 ) provided at an indoor unit is connected via the secondcontrol valve ( 400 ) to the first compression unit (C 1 ) and the second compression unit (C 2 ) and via the expansion valve ( 700 ) to the outdoor heat exchanger; and a first control valve ( 500 ) for controlling a refrigerant flow by selectively connecting the first compression unit (C 1 ) and the second compression unit (C 2 ) in series or in parallel. As the first compression unit (C 1 ) and the second compression unit (C 2 ) are selectively connected to each other in series or in parallel, a capacity of the air conditioner is varied according to a change of an indoor temperature and fabrication cost is minimized.

This is a National Phase Application which claims the benefits ofPCT/KR2004/003289 filed 14 Dec. 2004, which is hereby incorporated byreference for all purposes as if fully set forth herein.

TECHNICAL FIELD

The present invention relates to an air conditioner and a driving methodthereof, and more particularly, to an air conditioner capable of varyinga capacity according to a variance of an indoor temperature and capableof minimizing a fabrication cost, and a driving method thereof.

BACKGROUND ART

Generally, an air conditioner maintains an indoor temperature as apreset state thereby to maintain an indoor room as a comfortable state.

The air conditioner includes a refrigerating cycle system. Therefrigerating cycle system is composed of: a compressor for compressinga refrigerant; a condenser for condensing the refrigerant compressed inthe compressor and emitting heat to outside; an expansion valve forlowering a pressure of the refrigerant condensed by the condenser; andan evaporator for evaporating a refrigerant that has passed through theexpansion valve and absorbing external heat.

The compressor, the condenser, the expansion valve, and the evaporatorare connected to one another by a connection pipe thereby to form onecycle.

In the refrigerating cycle system, when the compressor is operated aspower is supplied to the compressor, a refrigerant of a high temperatureand high pressure discharged from the compressor sequentially passesthrough the condenser, the expansion valve, and the evaporator, and thenis sucked into the compressor. The above processes are repeated. Duringthe above process, heat is generated in the condenser, and cool air isformed as the evaporator absorbs external heat. The heat generated inthe condenser and the cool air formed in the evaporator are selectivelycirculated into an indoor room, thereby maintaining the indoor room as acomfortable state.

The air conditioner can be implemented as various shapes according to aninstallation condition. For example, the air conditioner is mounted inone casing with the refrigerating cycle system, and an air duct and ablowing fan are provided in the casing. The air conditioner is generallyinstalled at a window of an indoor side in order to maintain arelatively small indoor room as a comfortable state.

As another example, the air conditioner is composed of an indoor unitand an outdoor unit. The indoor unit includes a heat exchanger servingas an evaporator at the time of performing an air conditioning. Theoutdoor unit includes a heat exchanger serving as a condenser at thetime of performing an air conditioning, and a compressor. The indoorunit is installed at an indoor room, and the outdoor unit is installedat an outdoor room.

As still another example, the air conditioner is composed of: oneoutdoor unit; and a plurality of indoor units connected to the outdoorunit and respectively installed at an indoor room. A compressor mountedat the outdoor unit has a great capacity, or two compressors are mountedat the outdoor unit.

Generally, a compressor converts an electric energy into a kineticenergy, and compresses a refrigerant by the kinetic energy. Thecompressor includes a motor part for generating a driving force; and acompression part for compressing a refrigerant by receiving the drivingforce of the motor part. The compressor can be divided into a rotarycompressor, a scroll compressor, a reciprocal compressor, etc. accordingto a compression mechanism of a refrigerant.

Among the above compressors, the rotary compressor, the scrollcompressor, etc. are mainly used in the air conditioner.

In the fabrication process of the air conditioner, the most importantfactor is to minimize a fabrication cost for a high competitiveness, andis to minimize an energy consumption at the time of operating the airconditioner.

Especially, as the oil usage amount is increased worldwide and thus theoil price is increased, an air conditioner capable of minimizing anenergy consumption is being much required. When the energy consumptionof the air conditioner is minimized, the environment pollution isminimized.

In order to minimize the energy consumption of the air conditioner, theair conditioner has to be driven according to a load of an indoor roomwhere the air conditioner is installed, that is, according to atemperature of an indoor room. That is, when a temperature of an indoorroom is drastically increased, the air conditioner is driven to generatemuch cold air in order to maintain a preset indoor temperature. On thecontrary, when a temperature of an indoor room is minutely varied, theair conditioner is driven to generate less cold air in order to maintaina preset indoor temperature.

To satisfy the above condition, an amount of a refrigerant dischargedfrom a compressor, a main component for driving a refrigerating cyclesystem is controlled.

In order to control a discharge amount of a refrigerant from thecompressor, an inverter motor for varying an rpm of a driving motorconstituting the compressor is used. The rpm of the driving motor of thecompressor is controlled according to a condition of an indoor roomwhere the air conditioner is installed, thereby controlling an amount ofa refrigerant discharged from the compressor. As the discharge amount ofthe refrigerant is varied, heat generated in the condenser and cold airgenerated in the evaporator are controlled.

However, in case of applying the inverter motor to the driving motor ofthe compressor, the fabrication cost of the air conditioner is increasedsince the inverter motor is very expensive thereby to lower the pricecompetitiveness.

According to this, it is required to vary a capacity of an airconditioner according to a condition of an indoor room where the airconditioner is installed by controlling an amount of a refrigerantdischarged from a compressor under a state that a general motor that isnot provided with a control drive is applied to the compressor.

DISCLOSURE OF INVENTION Technical Problem

Therefore, an object of the present invention is to provide an airconditioner capable of varying a capacity thereof according to avariation of an indoor temperature and capable of minimizing afabrication cost, and a driving method thereof.

Technical Solution

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described herein,there is provided an air conditioner comprising: a first compressionunit and a second compression unit for respectively compressing arefrigerant; an outdoor heat exchanger provided at an outdoor unit andconnected to the first compression unit and the second compression unit;an indoor heat exchanger provided at an indoor unit and connected to thefirst compression unit, the second compression unit, and the outdoorheat exchanger; and a refrigerant guiding means for controlling arefrigerant flow by connecting the first compression unit and the secondcompression unit in series or in parallel so that a refrigerant can beconsecutively or respectively compressed in the first compression unitand in the second compression unit and then discharged.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described herein,there is also provided a method for driving an air conditioner having afirst compression unit and a second compression unit comprising thesteps of: starting to drive the air conditioner; selecting a saving modeor a power mode according to a preset condition; controlling arefrigerant flow in series so that a refrigerant can be compressed inthe first compression unit and then compressed in the second compressionunit at the time of the saving mode; and controlling a refrigerant flowin parallel so that a refrigerant can be respectively compressed in thefirst compression unit and the second compression unit at the time ofthe power mode.

The foregoing and other objects, features, aspects and advantages of thepresent invention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

DESCRIPTION OF DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

In the drawings:

FIG. 1 is a piping diagram showing a first embodiment of an airconditioner according to the present invention;

FIG. 2 is a piping diagram showing a second embodiment of the airconditioner according to the present invention;

FIG. 3 is a view showing a driving method of the air conditioneraccording to the present invention;

FIGS. 4 and 5 are piping diagrams respectively showing an operationstate of the air conditioner in a power mode and in a saving modeaccording to the first embodiment of the present invention; and

FIGS. 6 and 7 are piping diagrams respectively showing an operationstate of the air conditioner in a power mode and in a saving modeaccording to the second embodiment of the present invention.

BEST MODE

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings.

An air conditioner and a driving method of the air conditioner accordingto the present invention will be explained with reference to theattached drawings as follows.

FIG. 1 is a piping diagram showing a first embodiment of an airconditioner according to the present invention.

As shown, the air conditioner comprises: an indoor unit including anindoor heat exchanger 100 and installed at an indoor room; an outdoorunit including an outdoor heat exchanger 200 and installed at an outdoorroom; a first compression unit C1 and a second compression unit C2installed at the outdoor unit, for respectively compressing arefrigerant; connection pipes for connecting the indoor heat exchanger100, the outdoor heat exchanger 200, the first compression unit C1, andthe second compression unit C2 as one cycle; and a refrigerant guidingmeans for controlling a refrigerant flow so that a refrigerant can flowto the first compression unit C1 and the second compression unit C2 inseries or in parallel.

The first compression unit C1 and the second compression unit C2 areprovided in one hermetic container 310, and respectively compress arefrigerant by a driving force of one driving motor 320 mounted in thehermetic container 310. The first compression unit C1 and the secondcompression unit C2 constitute a two-stage type compressor 300 having aflow path of a refrigerant for sucking a refrigerant to the compressionunit C1 and the second compression unit C2 and discharging therefrigerant. The driving motor 320 is a constant speed motor.

The flow path of a refrigerant of the two-stage type compressor 300includes: a first suction pipe 330 for guiding a refrigerant to besucked into a compression space of the first compression unit C1; asecond suction pipe 340 for guiding a refrigerant to be sucked into acompression space of the second compression unit C2; a first dischargepipe 350 coupled to the hermetic container 310, for discharging arefrigerant discharged from the first compression unit C1 outside thehermetic container 310 via the hermetic container 310, and a seconddischarge pipe 360 coupled to the hermetic container 310, fordischarging a refrigerant discharged from the second compression unit C2outside the hermetic container 310.

A chamber 370 for containing a refrigerant discharged from the secondcompression unit C2 is provided between the second compression unit C2and the second discharge pipe 360. The chamber 370 is formed by a cover380 coupled to a lower surface of the second compression unit C2.

A second control valve 400 for controlling a refrigerant discharged froma compression unit group including the first compression unit C1 and thesecond compression unit C2 to selectively flow to the outdoor heatexchanger 200 or the indoor heat exchanger 100 is provided at theconnection pipes.

The second control valve 400 is preferably a four-way valve.

The refrigerant guiding means includes: a first control valve 500 forcontrolling a flow direction of a refrigerant; an inlet connection pipe610 connected to the first control valve 500, for introducing arefrigerant to the first control valve 500 from the indoor heatexchanger 100 or the outdoor heat exchanger 200, a first connection pipe620 for connecting the inlet connection pipe 610 to the first suctionpipe 330, a suction side of the first compression unit C1; a secondconnection pipe 630 for connecting the first control valve 500 to thesecond suction pipe 340, a suction side of the second compression unitC2; an outlet connection pipe 640 connected to the first control valve500, for discharging a refrigerant to the indoor heat exchanger 100 orthe outdoor heat exchanger 200; a third connection pipe 650 forconnecting the outlet connection pipe 640 to the second discharge pipe360, a discharge side of the second compression unit C2; and anopen/close valve 660 mounted at the outlet connection pipe 640, foropening and closing a flow channel of a refrigerant.

A discharge side of the first compression unit C1 is connected to thefirst control valve 500 by the first discharge pipe 350.

The open/close valve 660 is positioned between the first control valve500 and a connection part between the outlet connection pipe 640 and thethird connection pipe 650.

The first control valve 500 is preferably a four-way valve.

The outlet connection pipe 640 connected to the first control valve 500is connected to the second control valve 400, and the inlet connectionpipe 610 connected to the first control valve 500 is connected to thesecond control valve 400. Also, a fourth connection pipe 670 connectedto an inlet of the outdoor heat exchanger 200 is connected to the secondcontrol valve 400, and a fifth connection pipe 680 connected to anoutlet of the indoor heat exchanger 100 is connected to the secondcontrol valve 400.

An outlet side of the outdoor heat exchanger 200 and an inlet side ofthe indoor heat exchanger 100 are connected to each other by a sixthconnection pipe 690. An expansion valve (or a capillary tube) 700 ismounted at the sixth connection pipe 690.

An unexplained reference numeral 390 denotes an accumulator.

FIG. 2 is a piping diagram showing a second embodiment of the airconditioner according to the present invention, in which the samereference numerals were given to the same parts as those of the firstembodiment.

As shown, the air conditioner has the first compression unit C1 and thesecond compression unit C2. The first compression unit C1 and the secondcompression unit C2 serve as a first compressor and a second compressor,respectively. The first connection unit C1 and the second connectionunit C2 are connected to the indoor heat exchanger 100, the outdoor heatexchanger 200, etc. by connection pipes to constitute one cycle. The airconditioner includes a refrigerant guiding means for controlling arefrigerant flow by connecting the first compression unit C1 to thesecond compression unit C2 in series or in parallel so that arefrigerant can be consecutively or respectively compressed in the firstcompression unit C1 and in the second compression unit C2 and thendischarged.

The compressor includes a driving motor part mounted in the hermeticcontainer and generating a driving force; and a compressing part forcompressing a refrigerant by receiving the driving force of the drivingmotor part. Suction pipes 820 and 920 for sucking a refrigerant areconnected to hermetic containers 810 and 910 constituting the firstcompressor and the second compressor, and discharge pipes 830 and 930for discharging a compressed refrigerant are connected to the hermeticcontainers 810 and 910. A driving motor constituting the driving motorpart is a constant speed motor. As the compressor, a rotary compressor,a scroll compressor, etc. can be applied.

A second control valve 400 for controlling a refrigerant discharged froma compression unit group including the first compression unit C1 and thesecond compression unit C2 to selectively flow to the outdoor heatexchanger 200 or the indoor heat exchanger 100 is provided at theconnection pipes.

The second control valve 400 is preferably a four-way valve.

The refrigerant guiding means includes: a first control valve 500 forcontrolling a flow direction of a refrigerant; an inlet connection pipe610 connected to the first control valve 500, for introducing arefrigerant to the first control valve 500 from the indoor heatexchanger 100 or the outdoor heat exchanger 200; a first connection pipe620 for connecting the inlet connection pipe 610 to the suction pipe 820of the first compression unit C1, the first compressor; a secondconnection pipe 630 for connecting the first control valve 500 to thesuction pipe 920 of the second compression unit C2, the secondcompressor; an outlet connection pipe 640 connected to the first controlvalve 500, for discharging a refrigerant to the indoor heat exchanger100 or the outdoor heat exchanger 200, a third connection pipe 650 forconnecting the outlet connection pipe 640 to the discharge pipe 930 ofthe second compression unit C2; and an open/close valve 660 mounted atthe outlet connection pipe 640, for opening and closing a flow path of arefrigerant.

The discharge pipe 830 of the first compression unit C1, the firstcompressor is connected to the first control valve 500 by the firstdischarge pipe 350.

The open/close valve 660 is positioned between the first control valve500 and a connection part between the outlet connection pipe 640 and thethird connection pipe.

The first control valve 500 is preferably a four-way valve.

The outlet connection pipe 640 connected to the first control valve 500is connected to the second control valve 400, and the inlet connectionpipe 610 connected to the first control valve 500 is connected to thesecond control valve 400. Also, a fourth connection pipe 670 connectedto an inlet of the outdoor heat exchanger 200 is connected to the secondcontrol valve 400, and a fifth connection pipe 680 connected to anoutlet of the indoor heat exchanger 100 is connected to the secondcontrol valve 400.

An outlet side of the outdoor heat exchanger 200 and an inlet side ofthe indoor heat exchanger 100 are connected to each other by a sixthconnection pipe 690. An expansion valve (or a capillary tube) 700 ismounted at the sixth connection pipe 690.

FIG. 3 is a view showing a driving method of an air conditioneraccording to the present invention.

As shown, a method for driving an air conditioner comprises the stepsof: starting to drive the air conditioner; selecting a saving mode or apower mode according to a preset condition; controlling a refrigerantflow in series so that a refrigerant can be compressed in the firstcompression unit C1 and then compressed in the second compression unitC2 at the time of the saving mode; and controlling a refrigerant flow inparallel so that a refrigerant can be respectively compressed in thefirst compression unit C1 and the second compression unit C2 at the timeof the power mode.

The saving mode and the power mode can be set according to a temperaturecondition inside a space where the air conditioner is installed oraccording to a season condition.

The saving mode is to decrease an amount of a refrigerant dischargedfrom a compression unit group including the first compression unit C1and the second compression unit C2, and the power mode is to relativelyincrease an amount of a refrigerant discharged from the compression unitgroup. Generally, the saving mode is applied in spring and autumn, andthe power mode is applied in summer.

A refrigerant discharged from the first compression unit C1 and thesecond compression unit C2 is controlled to be selectively introducedinto the outdoor heat exchanger 200 or the indoor heat exchanger 100.

In case that at least two compression units are provided, thecompression units are connected in series in a saving mode, andconnected in parallel in a power mode.

Hereinafter, the air conditioner and effects of the driving methodthereof will be explained as follows.

First, the first embodiment of the air conditioner will be explained. Incase of the power mode, as shown in FIG. 4, the inlet connection pipe610 is connected to the second connection pipe 630, and the firstdischarge pipe 350 is connected to the outlet connection pipe 640 bycontrolling the first control valve 500. At the same time, the inletconnection pipe 610 is connected to the fifth connection pipe 680, andthe outlet connection pipe 640 is connected to the fourth connectionpipe 670 by controlling the second control valve 400.

Under this state, the driving motor 320 of the two-stage compressor isoperated, and the first compression unit C1 and the second compressionunit C2 are operated by receiving the driving force of the driving motor320. As the first compression unit C1 and the second compression unit C2are operated, a refrigerant that has passed through the indoor heatexchanger 100 flows through the fifth connection pipe 680 and the inletconnection pipe 610. A part of the refrigerant flowing through the inletconnection pipe 610 is sucked into the compression space of the firstcompression unit C1 through the first connection pipe 620 and the firstsuction pipe 330. Also, the rest part of the refrigerant flowing throughthe inlet connection pipe 610 is sucked into the compression space ofthe second compression unit C2 through the second connection pipe 630and the second suction pipe 340.

The refrigerant that has been sucked into the compression space of thefirst compression unit C1 is compressed in the first compression unit C1and is discharged, thereby being discharged to the outlet connectionpipe 640 through the inside of the hermetic container 310 and the firstdischarge pipe 350. At this time, the open/close valve 660 is opened.

Also, the refrigerant that has been sucked into the compression space ofthe second compression unit C2 is compressed in the second compressionunit C2 and is discharged, thereby being introduced into the outletconnection pipe 640 through the chamber 370, the second discharge pipe360, and the third connection pipe 650.

The refrigerant compressed in the first compression unit C1 and therefrigerant compressed in the second compression unit C2 are introducedinto the outdoor heat exchanger 200 through the outlet connection pipe640 and the fourth connection pipe 670. The refrigerant that has passedthrough the outdoor heat exchanger 200 is introduced into the indoorheat exchanger 100 through the sixth connection pipe 690, and therefrigerant that has passed through the indoor heat exchanger 100 isintroduced into the inlet connection pipe 610 through the fifthconnection pipe 680.

The refrigerant that has been introduced into the inlet connection pipe610 circulates a cycle with repeating the above processes. As the aboveprocesses are repeated, the outdoor heat exchanger 200 emits heatoutwardly, and the indoor heat exchanger 100 absorbs external heatthereby to form cool air.

At the time of the power mode, under a state that the first compressionunit C1 and the second compression unit C2 are connected to each otherin parallel, a refrigerant is respectively compressed in the firstcompression unit C1 and the second compression unit C2 and then isdischarged, thereby relatively increasing a discharge amount of arefrigerant.

When the power mode is applied to a heating operation, the outletconnection pipe 640 is connected to the fifth connection pipe 680, andthe inlet connection pipe 610 is connected to the fourth connection pipe670 by controlling the second control valve 400. At this time, theoutdoor heat exchanger 200 serves as an evaporator, and the indoor heatexchanger 100 serves as a condenser, thereby emitting heat outwardlyfrom the indoor heat exchanger 100.

At the time of the saving mode, as shown in FIG. 5, the first dischargepipe 350 is connected to the second connection pipe 630, and a port ofthe first control valve 500 connected to the inlet connection pipe 610is blocked by controlling the first control valve 500. Then, theopen/close valve 660 is closed. At the same time, the inlet connectionpipe 610 is connected to the fifth connection pipe 680, and the outletconnection pipe 640 is connected to the fourth connection pipe 670 bycontrolling the second control valve 400.

Under this state, when the driving motor 320 of the two-stage compressoris operated, the first compression unit C1 and the second compressionunit C2 are operated by receiving the driving force of the driving motor320. As the first compression unit C1 and the second compression unit C2are operated, a refrigerant that has passed through the indoor heatexchanger 100 flows through the fifth connection pipe 680 and the inletconnection pipe 610. The refrigerant flowing through the inletconnection pipe 610 is sucked into the compression space of the firstcompression unit C1 through the first connection pipe 620 and the firstsuction pipe 330.

The refrigerant that has been sucked into the compression space of thefirst compression unit C1 is compressed in the first compression unit C1and is discharged, thereby being introduced into the second connectionpipe 630 through the inside of the hermetic container 310 and the firstdischarge pipe 350. Then, the refrigerant is sucked into the compressionspace of the second compression unit C2 through the second suction pipe340.

The refrigerant that has been sucked into the compression space of thesecond compression unit C2 is compressed in the second compression unitC2 and is discharged, thereby being introduced into the outletconnection pipe 640 through the chamber 370, the second discharge pipe360, and the third connection pipe 650.

The refrigerant flowing through the outlet connection pipe 640 isintroduced into the outdoor heat exchanger 200 through the fourthconnection pipe 670. The refrigerant that has been introduced into theoutdoor heat exchanger 200 is introduced into the indoor heat exchanger100 through the sixth connection pipe 690. Then, the refrigerantintroduced into the indoor heat exchanger 100 is introduced into theinlet connection pipe 610 through the fifth connection pipe 680.

The refrigerant that has been introduced into the inlet connection pipe610 circulates a cycle with repeating the above processes. As the aboveprocesses are repeated, the outdoor heat exchanger 200 emits heatoutwardly, and the indoor heat exchanger 100 absorbs external heatthereby to form cool air.

At the time of the saving mode, under a state that the first compressionunit C1 and the second compression unit C2 are connected to each otherin series, a refrigerant is consecutively compressed in the firstcompression unit C1 and in the second compression unit C2 and then isdischarged, thereby relatively decreasing a discharge amount of arefrigerant.

When the saving mode is applied to a heating operation, the outletconnection pipe 640 is connected to the fifth connection pipe 680, andthe inlet connection pipe 610 is connected to the fourth connection pipe670 by controlling the second control valve 400. At this time, theoutdoor heat exchanger 200 serves as an evaporator, and the indoor heatexchanger 100 serves as a condenser, thereby emitting heat outwardlyfrom the indoor heat exchanger 100.

An operation of the air conditioner according to the second embodimentof the present invention will be explained as follows.

At the time of a power mode for a cooling operation, as shown in FIG. 6,the inlet connection pipe 610 is connected to the second connection pipe630, and the first discharge pipe 350 is connected to the outletconnection pipe 640 by controlling the first control valve 500. Theopen/close valve 660 is opened. At the same time, the inlet connectionpipe 610 is connected to the fifth connection pipe 680, and the outletconnection pipe 640 is connected to the fourth connection pipe 670 bycontrolling the second control valve 400.

Under this state, when the first compressor and the second compressorare operated as power is applied to the first compressor, the firstcompression unit C1 and the second compressor, the second compressionunit C2, the refrigerant that has passed through the indoor heatexchanger 100 flows through the fifth connection pipe 680 and the inletconnection pipe 610. A part of the refrigerant flowing through the inletconnection pipe 610 is sucked into the first compression unit C1 throughthe first connection pipe 620. Also, the rest part of the refrigerantflowing through the inlet connection pipe 610 is sucked into the secondcompression unit C2 through the second connection pipe 630.

The refrigerant that has been sucked into the first compression unit C1is compressed in the first compression unit C1 and is discharged,thereby being discharged to the outlet connection pipe 640 through thefirst discharge pipe 350.

Also, the refrigerant that has been sucked into the second compressionunit C2 is compressed in the second compression unit C2 and isdischarged thereby being introduced into the outlet connection pipe 640through the third connection pipe 650.

The refrigerant compressed in the first compression unit C1 and therefrigerant compressed in the second compression unit C2 are introducedinto the outdoor heat exchanger 200 through the outlet connection pipe640 and the fourth connection pipe 670. The refrigerant that has passedthrough the outdoor heat exchanger 200 is introduced into the indoorheat exchanger 100 through the sixth connection pipe 690, and therefrigerant that has passed through the indoor heat exchanger 100 isintroduced into the inlet connection pipe 610 through the fifthconnection pipe 680.

The refrigerant that has been introduced into the inlet connection pipe610 circulates a cycle with repeating the above processes. As the aboveprocesses are repeated, the outdoor heat exchanger 200 emits heatoutwardly, and the indoor heat exchanger 100 absorbs external heatthereby to form cool air.

At the time of the power mode for a cooling operation, under a statethat the first compression unit C1 and the second compression unit C2are connected to each other in parallel, a refrigerant is respectivelycompressed in the first compression unit C1 and the second compressionunit C2 and then is discharged, thereby relatively increasing adischarge amount of a refrigerant.

When the power mode is applied to a heating operation, the secondcontrol valve 400 is adjusted in the same manner as the aforementionedmanner.

At the time of the saving mode for a cooling operation, as shown in FIG.7, the first discharge pipe 350 is connected to the second connectionpipe 630, and a port of the first control valve 500 connected to theinlet connection pipe 610 is blocked by controlling the first controlvalve 500. Then, the open/close valve 660 is closed. At the same time,the inlet connection pipe 610 is connected to the fifth connection pipe680, and the outlet connection pipe 640 is connected to the fourthconnection pipe 670 by controlling the second control valve 400.

Under this state, when the first compressor, the first compression unitC1 and the second compressor, the second compression unit C2 areoperated as power is supplied thereto, a refrigerant that has passedthrough the indoor heat exchanger 100 is sucked into the firstcompressor via the fifth connection pipe 680, the inlet connection pipe610, and the first connection pipe 620.

The refrigerant sucked into the first compressor is compressed in thefirst compressor and is discharged, thereby being sucked into the secondcompressor through the first discharge pipe 350 and the secondconnection pipe 630. The refrigerant compressed in the second compressorand discharged is introduced into the inlet connection pipe 640 throughthe third connection pipe 650.

The refrigerant that has been introduced into the outlet connection pipe640 is introduced into the outdoor heat exchanger 200 through the fourthconnection pipe 670. Then, the refrigerant that has been introduced intothe outdoor heat exchanger 200 is introduced into the indoor heatexchanger 100 through the sixth connection pipe 690, and then isintroduced into the inlet connection pipe 610 through the fifthconnection pipe 680.

The refrigerant that has been introduced into the inlet connection pipe610 circulates a cycle with repeating the above processes. As the aboveprocesses are repeated, the outdoor heat exchanger 200 emits heatoutwardly, and the indoor heat exchanger 100 absorbs external heatthereby to form cool air.

At the time of the saving mode, under a state that the first compressionunit C1 and the second compression unit C2 are connected to each otherin series, a refrigerant is consecutively compressed in the firstcompression unit C1 and in the second compression unit C2 and then isdischarged, thereby relatively decreasing a discharge amount of arefrigerant.

When the saving mode is applied to a heating operation, the secondcontrol valve 400 is adjusted in the same manner as the aforementionedmanner.

INDUSTRIAL APPLICABILITY

As aforementioned, according to the air conditioner and the drivingmethod thereof according to the present invention, the air conditioneris driven by varying a capacity according to a temperature change or aseason change, thereby decreasing a consumption power of the airconditioner. According to this, a user's satisfaction degree is enhancedand a price competitiveness is high.

Also, since the capacity of the air conditioner is varied with using acheap constant speed motor, the fabrication cost is decreased.

As the present invention may be embodied in several forms withoutdeparting from the spirit or essential characteristics thereof, itshould also be understood that the above-described embodiments are notlimited by any of the details of the foregoing description, unlessotherwise specified, but rather should be construed broadly within itsspirit and scope as defined in the appended claims, and therefore allchanges and modifications that fall within the metes and bounds of theclaims, or equivalence of such metes and bounds are therefore intendedto be embraced by the appended claims.

1. An air conditioner comprising: a first compression unit and a secondcompression unit for compressing a refrigerant; an outdoor heatexchanger provided at an outdoor unit and connected to the firstcompression unit and the second compression unit; an indoor heatexchanger provided at an indoor unit and connected to the firstcompression unit, the second compression unit, and the outdoor heatexchanger; and a refrigerant guiding means for controlling a refrigerantflow by selectively connecting the first compression unit and the secondcompression unit in series or in parallel so that a refrigerant can beconsecutively or respectively compressed in the first compression unitand in the second compression unit and then discharged, wherein therefrigerant guiding means includes: a first control valve forcontrolling a flow direction of a refrigerant; an inlet connection pipeconnected to the first control valve; a first connection pipe connectedto a suction side of the first compression unit; a first discharge pipefor connecting a discharge side of the first compression unit and thefirst control valve; a second connection pipe for connecting the firstcontrol valve to a suction side of the second compression unit; anoutlet connection pipe connected to the first control valve; a thirdconnection pipe connected to a discharge side of the second compressionunit; and an open/close valve mounted at the outlet connection pipe, foropening and closing a flow path of a refrigerant.
 2. The air conditionerof claim 1, wherein the first compression unit is a first compressorincluding: a driving motor part mounted in a hermetic container forgenerating a driving force; and a compression part for compressing arefrigerant by receiving a driving force of the driving motor part, andthe second compression unit is a second compressor including: a drivingmotor part mounted in a hermetic container for generating a drivingforce; and a compression part for compressing a refrigerant by receivinga driving force of the driving motor part.
 3. The air conditioner ofclaim 2, wherein the driving motor part is rotated with a constantspeed.
 4. The air conditioner of claim 1, wherein the first compressionunit and the second compression unit are provided in one hermeticcontainer, respectively compress a refrigerant by receiving a drivingforce of one driving motor, and constitute a two-stage type compressorhaving a flow path of a refrigerant through which a refrigerant issucked into the first compression unit and the second compression unitand then is discharged.
 5. The air conditioner of claim 4, wherein thedriving motor is a constant speed motor.
 6. The air conditioner of claim4, wherein the flow path of a refrigerant of the two-stage typecompressor includes: a first suction pipe for guiding a refrigerant tobe sucked into a compression space of the first compression unit; asecond suction pipe for guiding a refrigerant to be sucked into acompression space of the second compression unit; a first discharge pipecoupled to the hermetic container, for discharging a refrigerantdischarged from the first compression unit outside the hermeticcontainer via the hermetic container; and a second discharge pipecoupled to the hermetic container, for discharging a refrigerantdischarged from the second compression unit outside the hermeticcontainer.
 7. The air conditioner of claim 6, wherein a chamber forcontaining a refrigerant discharged from the second compression unit isprovided between the second compression unit and the second dischargepipe.
 8. The air conditioner of claim 1, wherein the open/close valve ispositioned between the first control valve and a connection part betweenthe outlet connection pipe and the third connection pipe.
 9. The airconditioner of claim 1, wherein the first control valve is a four-wayvalve.
 10. The air conditioner of claim 1, further comprising; a secondcontrol valve connected to the outlet connection pipe and the inletconnection pipe for controlling a refrigerant discharged from acompression unit group to selectively flow to the outdoor heat exchangeror the indoor heat exchanger, wherein the compression unit groupincludes the first compression unit and the second compression unit. 11.The air conditioner of claim 10, wherein the second control valve is afour-way valve.
 12. A method for driving the air conditioner of claim 1,comprising the steps of: starting to drive the air conditioner;selecting a saving mode or a power mode according to a preset condition;controlling a refrigerant flow in series so that a refrigerant iscompressed in the first compression unit and then compressed in thesecond compression unit at the time of the saving mode; and controllinga refrigerant flow in parallel so that a refrigerant is respectivelycompressed in the first compression unit and in the second compressionunit at the time of the power mode.
 13. The method of claim 12, whereina refrigerant discharged from the first compression unit and the secondcompression unit is controlled to selectively flow to the outdoor heatexchanger or the indoor heat exchanger.
 14. The method of claim 12,wherein the compression units are connected to one another in series inthe saving mode and are connected to one another in parallel in thepower mode.